The Hagstrom Concord bass was produced in four batches between 1965 and 1971. According to shipping data there were three batches of Concord C1, and one batch of the Concord Deluxe C2, although this is actually incomplete. A few examples have turned up with batch numbers other than those listed in the data, although it is not clear how big these batches were. There were some small changes over the course of production; early models (from batch 647) had a floating rosewood bridge, (later changing to a fixed bridge), a rectangular tailpiece (changing to the Hagstrom Crest design) and a plain (or no?) scratchplate.